The invention relates to a method for joining a plurality of reticles for use in producing a semiconductor layout pattern, so that said reticles will collectively map a circuit arrangement on a semiconductor substrate whilst providing a plurality of matching patterns that are each geometrically linked to a respective particular reticle as being furthermore recited in the preamble of Claim 1. Through ascertaining correspondence among various matching patterns the correct geometrical correspondence among the associated reticles is established. In this manner it has proven possible to produce extremely large semiconductor substrates that are used in fields such as digital storage arrays and camera pickup facilities. The art has recognized that the matching patterns are generally too big to fit in the normal array granularity, so that they will generally be positioned at an edge of “their” reticle. In practice, this will allow a maximum array size of 2×2 patterns, and in many instances, only a 1×n pattern, wherein n is an integer of 2 or more.
Hereinafter, the term reticle is used as corresponding to a “photomask”, wherein a photomask comprises all functionality necessary in the ultimate semiconductor chip. It is possible to use a plurality of reticles to therefrom construct an extended chip, see FIG. 2 hereinafter. Alternatively, a reticle can be subdivided into sub-reticles, wherein various sub-reticles may project respective different functionality parts, so that the whole chip must necessarily be formed by using sub-reticles of more than one different class, see FIGS. 4 and 6 hereinafter.
As expectable, ever larger circuit areas are being requested, and the sizes of the above patterns have been found insufficient. By themselves, larger patterns can be effected, at the cost of providing non-uniform partial reticles. By way of example, an array of 2×2 patterns can be realized through using four different reticles as discussed hereinafter with reference to FIG. 2. The cost of both providing more non-uniform reticles, and also the cost of changing from one reticle to another have been found inappropriate. In consequence, the matching of the reticles should be effected on a higher level.
In consequence, amongst other things, it is an object of the present invention to allow the positioning of various reticles with respect to each other in such manner that the matching patterns are external both to the geometrical payload of the various sub-reticles and also external to the eventual circuit produced by the arrangement.